The invention relates generally to a color printer.
More particularly, the invention relates to a method of and an arrangement for adjusting color saturation in a color printer, especially a video printer.
During the making of a print in a color video printer or CRT printer, i.e. cathode ray tube printer, instant print color paper is consecutively exposed to radiation in the three primary colors. When standard video signals are used and the exposures in the primary colors are regulated in such a manner that the peak white light intensity does not result in overexposure, areas in which maximum saturation of the primary colors red, green, blue and the complementary colors yellow, magenta, cyan exists are darkened upon reproduction. The brightness found in conventional prints is not achieved.
Investigations of this problem have revealed that an image may be reproduced on instant print color paper without significant darkening if the individual exposures in the primary colors can be performed with red, green and blue light of high illuminating color and purity. However, when a television test image is printed on instant print color paper and such image contains, in addition to the primary colors red, green, blue and the complementary colors yellow, magenta, cyan, a white area with maximum dominant amplitude, i.e. an area of peak white intensity, the exposure is determined by the white signal. If overexposure of the white area is avoided by appropriate selection of the amplitude of the white signal, insufficient exposure of areas saturated in the primary and complementary colors is obtained and these colors are darkened upon reproduction. Consequently, the brightness of the print is substantially less than that of conventional prints.